Deserializers as singleton

spectrum/src/main/java/io/github/giulong/spectrum/internals/jackson/deserializers/BrowserDeserializer.java

@@ -3,13 +3,23 @@
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import io.github.giulong.spectrum.browsers.*;
+import lombok.NoArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.IOException;
 
+import static lombok.AccessLevel.PRIVATE;
+
 @Slf4j
+@NoArgsConstructor(access = PRIVATE)
 public class BrowserDeserializer extends InterpolatedDeserializer<Browser<?, ?, ?>> {
 
+    private static final BrowserDeserializer INSTANCE = new BrowserDeserializer();
+
+    public static BrowserDeserializer getInstance() {
+        return INSTANCE;
+    }
+
     @Override
     public Browser<?, ?, ?> deserialize(final JsonParser jsonParser, final DeserializationContext deserializationContext) throws IOException {
         final String value = jsonParser.getValueAsString();

spectrum/src/main/java/io/github/giulong/spectrum/internals/jackson/deserializers/DurationDeserializer.java

@@ -3,14 +3,24 @@
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.JsonDeserializer;
+import lombok.NoArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.IOException;
 import java.time.Duration;
 
+import static lombok.AccessLevel.PRIVATE;
+
 @Slf4j
+@NoArgsConstructor(access = PRIVATE)
 public class DurationDeserializer extends JsonDeserializer<Duration> {
 
+    private static final DurationDeserializer INSTANCE = new DurationDeserializer();
+
+    public static DurationDeserializer getInstance() {
+        return INSTANCE;
+    }
+
     @Override
     public Duration deserialize(final JsonParser jsonParser, final DeserializationContext deserializationContext) throws IOException {
         final int value = jsonParser.getValueAsInt();

spectrum/src/main/java/io/github/giulong/spectrum/internals/jackson/deserializers/InterpolatedBooleanDeserializer.java

@@ -2,13 +2,23 @@
 
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.DeserializationContext;
+import lombok.NoArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.IOException;
 
+import static lombok.AccessLevel.PRIVATE;
+
 @Slf4j
+@NoArgsConstructor(access = PRIVATE)
 public class InterpolatedBooleanDeserializer extends InterpolatedDeserializer<Boolean> {
 
+    private static final InterpolatedBooleanDeserializer INSTANCE = new InterpolatedBooleanDeserializer();
+
+    public static InterpolatedBooleanDeserializer getInstance() {
+        return INSTANCE;
+    }
+
     @Override
     public Boolean deserialize(final JsonParser jsonParser, final DeserializationContext deserializationContext) throws IOException {
         final String value = jsonParser.getValueAsString();

spectrum/src/main/java/io/github/giulong/spectrum/internals/jackson/deserializers/InterpolatedObjectDeserializer.java

@@ -5,20 +5,28 @@
 import com.fasterxml.jackson.databind.JsonDeserializer;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.JsonNodeType;
+import lombok.NoArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.IOException;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import static io.github.giulong.spectrum.SpectrumSessionListener.VARS;
+import static lombok.AccessLevel.PRIVATE;
 
 @Slf4j
+@NoArgsConstructor(access = PRIVATE)
 public class InterpolatedObjectDeserializer extends JsonDeserializer<Object> {
 
+    private static final InterpolatedObjectDeserializer INSTANCE = new InterpolatedObjectDeserializer();
     private static final Pattern INT_PATTERN = Pattern.compile("(?<placeholder>\\$<(?<varName>[\\w.]+)(:-(?<defaultValue>[\\w~.:/\\\\]*))?>)");
     private static final Pattern NUMBER = Pattern.compile("-?\\d+(.\\d+|,\\d+)?");
 
+    public static InterpolatedObjectDeserializer getInstance() {
+        return INSTANCE;
+    }
+
     @Override
     public Object deserialize(final JsonParser jsonParser, final DeserializationContext deserializationContext) throws IOException {
         final JsonNode jsonNode = jsonParser.readValueAsTree();

spectrum/src/main/java/io/github/giulong/spectrum/internals/jackson/deserializers/LogbackLogLevelDeserializer.java

@@ -4,11 +4,21 @@
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.JsonDeserializer;
+import lombok.NoArgsConstructor;
 
 import java.io.IOException;
 
+import static lombok.AccessLevel.PRIVATE;
+
+@NoArgsConstructor(access = PRIVATE)
 public class LogbackLogLevelDeserializer extends JsonDeserializer<Level> {
 
+    private static final LogbackLogLevelDeserializer INSTANCE = new LogbackLogLevelDeserializer();
+
+    public static LogbackLogLevelDeserializer getInstance() {
+        return INSTANCE;
+    }
+
     @Override
     public Level deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
         return Level.toLevel(jsonParser.getValueAsString());

spectrum/src/main/java/io/github/giulong/spectrum/internals/jackson/deserializers/UtilLogLevelDeserializer.java

@@ -3,12 +3,22 @@
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.JsonDeserializer;
+import lombok.NoArgsConstructor;
 
 import java.io.IOException;
 import java.util.logging.Level;
 
+import static lombok.AccessLevel.PRIVATE;
+
+@NoArgsConstructor(access = PRIVATE)
 public class UtilLogLevelDeserializer extends JsonDeserializer<Level> {
 
+    private static final UtilLogLevelDeserializer INSTANCE = new UtilLogLevelDeserializer();
+
+    public static UtilLogLevelDeserializer getInstance() {
+        return INSTANCE;
+    }
+
     @Override
     public Level deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
         return Level.parse(jsonParser.getValueAsString());

spectrum/src/main/java/io/github/giulong/spectrum/utils/YamlUtils.java

@@ -39,13 +39,13 @@ public static YamlUtils getInstance() {
             .setDefaultMergeable(true)
             .registerModules(
                     new JavaTimeModule(),
-                    new SimpleModule().addDeserializer(Object.class, new InterpolatedObjectDeserializer()),
+                    new SimpleModule().addDeserializer(Object.class, InterpolatedObjectDeserializer.getInstance()),
                     new SimpleModule().addDeserializer(String.class, InterpolatedStringDeserializer.getInstance()),
-                    new SimpleModule().addDeserializer(boolean.class, new InterpolatedBooleanDeserializer()),
-                    new SimpleModule().addDeserializer(java.util.logging.Level.class, new UtilLogLevelDeserializer()),
-                    new SimpleModule().addDeserializer(Level.class, new LogbackLogLevelDeserializer()),
-                    new SimpleModule().addDeserializer(Duration.class, new DurationDeserializer()),
-                    new SimpleModule().addDeserializer(Browser.class, new BrowserDeserializer())
+                    new SimpleModule().addDeserializer(boolean.class, InterpolatedBooleanDeserializer.getInstance()),
+                    new SimpleModule().addDeserializer(java.util.logging.Level.class, UtilLogLevelDeserializer.getInstance()),
+                    new SimpleModule().addDeserializer(Level.class, LogbackLogLevelDeserializer.getInstance()),
+                    new SimpleModule().addDeserializer(Duration.class, DurationDeserializer.getInstance()),
+                    new SimpleModule().addDeserializer(Browser.class, BrowserDeserializer.getInstance())
             );
 
     private final ObjectWriter writer = new YAMLMapper()

spectrum/src/test/java/io/github/giulong/spectrum/internals/jackson/deserializers/BrowserDeserializerTest.java

@@ -49,6 +49,13 @@ public static void afterAll() {
         VARS.clear();
     }
 
+    @Test
+    @DisplayName("getInstance should return the singleton")
+    public void getInstance() {
+        //noinspection EqualsWithItself
+        assertSame(BrowserDeserializer.getInstance(), BrowserDeserializer.getInstance());
+    }
+
     @DisplayName("deserialize should delegate to the parent method passing the string value")
     @ParameterizedTest(name = "with value {0} we expect {1}")
     @MethodSource("valuesProvider")

spectrum/src/test/java/io/github/giulong/spectrum/internals/jackson/deserializers/DurationDeserializerTest.java

@@ -13,6 +13,7 @@
 import java.time.Duration;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.mockito.Mockito.when;
 
 @ExtendWith(MockitoExtension.class)
@@ -28,6 +29,13 @@ class DurationDeserializerTest {
     @InjectMocks
     private DurationDeserializer durationDeserializer;
 
+    @Test
+    @DisplayName("getInstance should return the singleton")
+    public void getInstance() {
+        //noinspection EqualsWithItself
+        assertSame(DurationDeserializer.getInstance(), DurationDeserializer.getInstance());
+    }
+
     @Test
     @DisplayName("deserialize should return the duration in seconds from the provided string")
     public void deserialize() throws IOException {

spectrum/src/test/java/io/github/giulong/spectrum/internals/jackson/deserializers/InterpolatedBooleanDeserializerTest.java

@@ -5,6 +5,7 @@
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
@@ -18,6 +19,7 @@
 
 import static io.github.giulong.spectrum.SpectrumSessionListener.VARS;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 import static org.mockito.Mockito.when;
 
@@ -46,6 +48,13 @@ public static void afterAll() {
         VARS.clear();
     }
 
+    @Test
+    @DisplayName("getInstance should return the singleton")
+    public void getInstance() {
+        //noinspection EqualsWithItself
+        assertSame(InterpolatedBooleanDeserializer.getInstance(), InterpolatedBooleanDeserializer.getInstance());
+    }
+
     @DisplayName("deserialize should delegate to the parent method passing the string value")
     @ParameterizedTest(name = "with value {0} we expect {1}")
     @MethodSource("valuesProvider")

spectrum/src/test/java/io/github/giulong/spectrum/internals/jackson/deserializers/InterpolatedObjectDeserializerTest.java

@@ -23,6 +23,7 @@
 import static com.github.stefanbirkner.systemlambda.SystemLambda.withEnvironmentVariable;
 import static io.github.giulong.spectrum.SpectrumSessionListener.VARS;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 import static org.junit.jupiter.params.provider.EnumSource.Mode.EXCLUDE;
 import static org.mockito.Mockito.mockStatic;
@@ -71,6 +72,13 @@ public static void afterAll() {
         VARS.clear();
     }
 
+    @Test
+    @DisplayName("getInstance should return the singleton")
+    public void getInstance() {
+        //noinspection EqualsWithItself
+        assertSame(InterpolatedObjectDeserializer.getInstance(), InterpolatedObjectDeserializer.getInstance());
+    }
+
     @Test
     @DisplayName("deserialize should delegate to the interpolatedStringDeserializer when the value is a string")
     public void deserializeStrings() throws IOException {

spectrum/src/test/java/io/github/giulong/spectrum/internals/jackson/deserializers/LogbackLogLevelDeserializerTest.java

@@ -3,8 +3,8 @@
 import ch.qos.logback.classic.Level;
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.DeserializationContext;
-import io.github.giulong.spectrum.internals.jackson.deserializers.LogbackLogLevelDeserializer;
 import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
@@ -18,6 +18,7 @@
 
 import static ch.qos.logback.classic.Level.*;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 import static org.mockito.Mockito.when;
 
@@ -34,6 +35,13 @@ class LogbackLogLevelDeserializerTest {
     @InjectMocks
     private LogbackLogLevelDeserializer logbackLogLevelDeserializer;
 
+    @Test
+    @DisplayName("getInstance should return the singleton")
+    public void getInstance() {
+        //noinspection EqualsWithItself
+        assertSame(LogbackLogLevelDeserializer.getInstance(), LogbackLogLevelDeserializer.getInstance());
+    }
+
     @DisplayName("deserialize should return the Logback level from the provided string")
     @ParameterizedTest(name = "with value {0} we expect {1}")
     @MethodSource("valuesProvider")

spectrum/src/test/java/io/github/giulong/spectrum/internals/jackson/deserializers/UtilLogLevelDeserializerTest.java

@@ -13,6 +13,7 @@
 
 import static java.util.logging.Level.INFO;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.mockito.Mockito.when;
 
 @ExtendWith(MockitoExtension.class)
@@ -26,7 +27,14 @@ class UtilLogLevelDeserializerTest {
     private DeserializationContext deserializationContext;
 
     @InjectMocks
-    private io.github.giulong.spectrum.internals.jackson.deserializers.UtilLogLevelDeserializer UtilLogLevelDeserializer;
+    private UtilLogLevelDeserializer UtilLogLevelDeserializer;
+
+    @Test
+    @DisplayName("getInstance should return the singleton")
+    public void getInstance() {
+        //noinspection EqualsWithItself
+        assertSame(UtilLogLevelDeserializer.getInstance(), UtilLogLevelDeserializer.getInstance());
+    }
 
     @Test
     @DisplayName("deserialize should return the log level from the provided string")